Amp repair where do I start

[LoveChet]

Thanks for all the help. Say hi to Tommy Emanual for me you see him. Gary Root

[LoveChet]

12AY7 V2
pin 1 plate 160v DC
1k hz 150 mv in
4 v signal pin 1 plate
Treble wiper at 5
1.2 v with fat pos 1
.75 v with fat pos 6
Bass pot no effect

[LoveChet]

Moving 2 V2B. 150vDC pin 6 plate.
I notice the 47pf cap going from treble wiper to pin 7 grid has been snipped.

[Tom Phillips]

Moving 2 V2B. 150vDC pin 6 plate. I notice the 47pf cap going from treble wiper to pin 7 grid has been snipped.

That 47pF cap is the standard Deluxe Reverb Bright cap. It is a common mod to sni9 it out of the circuit per the wishes of some players.
A clearer way to visualize the effect is to realize that the functionality is to bypass high treble frequencies from the hot side of the volume control to the wiper which is the output of the volume control. It's true that the cap also connects to the treble wiper only because the signal from the treble wiper feeds the hot side of the volume control.
See that attached snip of the relevant portion of the DR circuit.

[Helmholtz]

I definitely like a 47p bright cap.
It's an effective measure to counter the treble loss due to the Miller capacitance of the following stage.
Some Fender amp use a bright switch with a 120p cap, which is too much for me.

[LoveChet]

I probably snipped it years ago. I am a Chet Atkins fanatic and the mids are what (for me) drive the country deep tone.

[LoveChet]

On plate pin 6 of V2B I get about 12 V Signal max before the bottom of he sign wave starts to flatten out. I can push the volume past that by pushing the volume or treble controls above midrange and or removing more caps per a fat switch selection.

[LoveChet]

Even though I'm using a dummy load, i tend not to want to push the amp to max (dimeing) just to see how much each gain stage offers. Im assuming that pushing it to max can damage the output tubes and or the output transformer. Whats your take?

[Helmholtz]

It shouldn't be a problem at all to run the amp at full power for few minutes.
I always do full power testing. It's one of the most revealing amp tests.

[LoveChet]

[LoveChet]

I cracked it up. Is the distorted flat portion the normal distortion that some guitar players want ?

[LoveChet]

Moving on to master volume I'm 15v undistorted at point A on schematic which is just before the 22 meg. On the upstream side of 22meg I'm 3v but it's distorted

[LoveChet]

[LoveChet]

That 3v distorted is with push pull put so 22meg is shorted out. Pushed in I can get .3 v undistorted if I turn volume way down to 2

[Helmholtz]

Does the single sided clipping change when you swap power tubes in their sockets?
What is the scope's input sensitivity setting?
Does your scope have measuring functions?
For output power measurements the MV must be fully up.